Terrified pupils are led out of the building in single file after a gunman opened fire in their classrooms

Multiple gunshots heard alongside screams of horror as students hide in classroom during school shooting in Parkland, Florida

One user wrote: "This, ladies and gentlemen, if the face of a hero.

"Coach Aaron Feis was injured protecting a student in the shooting at Marjory Stoneman Douglas High School and, at last report, is in critical condition.

"He is a friend to all students that know him. He was always so nice to me when I went to school there, and I know he is close with my brother and his friends. Please, take a moment to send healing prayers for him."

Former student Andrew Hofmann, who coaches polo and swimming at the school, described the Aaron as “a quiet person” with a good sense of humour.

Nikolas Cruzis pinned down on the floor and arrested by cops in the nearby town of Coral Springs around two hours after going on a rampage

Watch the moment Florida high school gunman Nicolas Cruz is arrested in the street

He told the Miami Herald: “When there’s a funny joke he is always laughing for sure."

The school's athletic director Chris Hixon has also been confirmed as another victim of the shooting, however his condition is unknown.

Dan Jacob, who is athletic director at a neighbouring school in Coral Springs, told the Sun Sentinel: "“Chris is probably the nicest guy I have ever met. He would give you the shirt off his back. He does so much. That is terrible that it would happen to anybody. It is so senseless.

“I am crushed. … I am totally crushed.”

More tales of hero teachers are emerging as further details on the shooting, which also left 14 people wounded, become clear.

Ernest Rospierski assumed the fire alarm was a "code red" drill and began evacuating his pupils into the corridor when he spotted the gunman at the end of the hall.

He tried to turn back but was locked out of his classroom and pushed eight children into a 2.5ft alcove by the door, desperately trying to keep them out of the line of fire.